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Anatomy and Physiology of the Cardiovascular System. Prepared by Miss Fatima Hirzallah. The heart is a hollow, muscular organ situated in the space between lungs(mediastinum) , its about 12 cm in length & about 9 cm in width. Cardiac Muscle . Contract as a single unit

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slide2

The heart is a hollow, muscular organ situated in the space between lungs(mediastinum) , its about 12 cm in length & about 9 cm in width

cardiac muscle
Cardiac Muscle
  • Contract as a single unit
  • Simultaneous contraction due to depolarizing at the same time
  • Automaticity
slide4
The heart is about the size of a clenched fist and comprises.
  • The heart composd of four layers:
  • Endocardium,
  • Myocardium,
  • Epicardium,
  • and the pericardium..
slide5
endocardium is the inner layer and is consists of endothelial tissue that lines the inner surface of the heart and the cardiac valves.
  • The myocardiumis the middle layer and is composed of muscle fibers that enable the heart to pump.
  • Epicardium is the outer layer, is tightly adherent to the heart and the base of the great vessels.
  • A thin, fibrous, double-layered sac known as the pericardiumsurrounds the heart.
slide6
The outer layer is known as the parietal pericardium
  • and the inner layer is called the visceral pericardium
  • Between these two layers is a small amount of pericardial fluid (30 to 50 mL) that serves as a lubricant between the two layers
slide8
The heart consists of four chambers:
  • right and left atrium
  • right and left ventricles.
heart valves
Heart valves
  • The cardiac valves are composed of fibrous tissue and allow blood to flow in one direction.
  • The valves open and close as a result of blood flow and pressure differences.
slide10

The tricuspid and mitral valves are known as the atrioventricular (AV) valves because they are located between the atria and the ventricles.

  • The pulmonic and aortic valves are known as the semilunar valvesbecause each has three leaflets shaped like half-moons.
circulation of the blood
Circulation of the blood
  • The blood passes through the tricuspid valve into the right ventricle, which then pumps the blood through the pulmonic valve into the pulmonary circulation.
  • After gas exchange in the lungs, oxygenated blood returns to the left atrium, passes through the mitral valve, enters the left ventricle, passes through the aortic valve, and finally enters the aorta
coronary arteries
Coronary Arteries
  • The left and right coronary arteries and their branches supply arterial blood to the heart. These arteries originate from the aorta just above the aortic valve leaflets.
  • The heart has large metabolic requirements, extracting approximately 70% to 80% of the oxygen delivered (other organs consume, on average, 25%).
slide14
The left coronary artery has three branches.

1-the artery from the point of origin to the first major branch is called the left main coronary artery.

two bifurcations arise off the left main coronary artery

2- left anterior descending artery (LAD), which courses down the anterior wall of the heart

3-circumflex artery, which circles around to the lateral left wall of the heart.

slide15

The right side of the heart is supplied by the right coronary artery, which progresses around to the bottom or inferior wall of the heart.

  • The posterior wall of the heart receives its blood supply by an additional branch from the right coronary artery called the posterior descending artery.
slide17
The coronary arteries are perfused during diastole. An increase in heart rate shortens diastole and can decrease myocardial perfusion.
  • Patients, particularly those with coronary artery disease (CAD), can develop myocardial ischemia (inadequate oxygen supply) when the heart rate accelerates.
cardiac output
Cardiac Output
  • Cardiac output is the amount of blood pumped out of the ventricle .
  • The cardiac output in a resting adult is about 5 L per minute but varies greatly depending on the metabolic needs of the body. Cardiac output is computed by multiplying the stroke volume by the heart rate.
slide19

Stroke volume (SV) :The amount of blood ejected by the left ventricle with each heartbeat .

  • the heart rate is 60 to 80 beats per minute (bpm)
  • The average resting stroke volume is about 70 mL, and Cardiac output can be affected by changes in either stroke volume or heart rate.
cardiac output index
Cardiac Output/Index
  • Cardiac output
    • CO = HR (beats/minute) X SV (liters/beat)
    • Normal adult: 4-8 liters/minute
  • Cardiac index
    • CI = CO(liter/minute)/Body surface area (m2)
    • Normal adult: 2.8-4.2 liter/minute/m2
    • Normalizes liter flow to body size
stroke volume
Stroke Volume
  • Preload
  • Afterload
  • Contractility
stroke volume1
Stroke Volume
  • Preload
    • The amount of stretch placed on the cardiac muscle just prior to systole (the amount of the ventricle at end diastole)
    • Diastole : filling stage of cardiac cycle.
  • Afterload
    • The force or pressure at which the blood is ejected from the left ventricle
    • Equated with systemic vascular resistance (SVR)
slide23
Contractilityis a term used to denote the force generated by the contracting myocardium under any given condition
  • The resistance of the systemic BP to left ventricular ejection is called systemic vascular resistance.
  • The resistance of the pulmonary BP to right ventricular ejection is called pulmonary vascular resistance

.

slide24

The percentage of the end-diastolic volume that is ejected with each stroke is called the ejection fraction (EF)

(EF) = 50-70%

slide26
HEALTH HISTORY AND
  • CLINICAL MANIFESTATIONS

For the patient experiencing an acute MI, the nurse obtains the health history using a few specific questions about the onset and severity of chest discomfort, associated symptoms, current medications, and allergies.

At the same time, the nurse observes the patient’s general appearance and evaluates hemodynamic status (heart rate and rhythm, BP).

slide27
Cardiac Signs and Symptoms

• Chest pain or discomfort (angina pectoris, MI, valvular heart disease) Shortness of breath or dyspnea (MI, left ventricular failure, HF)

• Edema and weight gain (right ventricular failure, HF)

• Palpitations (dysrhythmias resulting from myocardial ischemia, stress, electrolyte imbalance)

slide28

Fatigue (earliest symptom associated with several cardiovascularndisorders)

• Dizziness and syncope or loss of consciousness (postural

hypotension, dysrhythmias, vasovagal effect,cerebrovascular disorders)

physical exam
Inspection

General appearance

Jugular venous distension (JVD)

Skin

Extremities

Palpation

Pulses

Point of maximal impulse (PMI)

Percussion

Auscultation

Good stethoscope

Positioning

Normal tones – S1/S2

Extra tones – S3/S4

Murmurs

Rubs

Physical Exam
heart sounds
HEART SOUNDS

HEART SOUNDS

The normal heart sounds, S1 and S2, are produced primarily by

the closing of the heart valves. The time between S1 and S2 corresponds to systole This is normally shorter than the

time between S2 and S1 (diastole). As the heart rate increases diastole shortens.

S1—First Heart Sound. Closure of the mitral and tricuspid valves

creates the first heart sound (S1),

S2—Second Heart Sound. Closing of the aortic and pulmonic valves produces the second heart sound (S2).

slide34
Murmurs are created by the turbulent flow of blood.
  • The causes of the turbulence may be a critically narrowed valve,
  • a malfunctioning valve that allows regurgitant blood flow,
  • a congenital defect of the ventricular wall, a defect between the aorta and the pulmonary artery,
diagnostic evaluation
Diagnostic Evaluation
  • Laboratory test(Cardiac Labs)
  • Chest X-ray
  • ECG
  • CARDIAC STRESS TESTING
  • ECHOCARDIOGRAPHY(ECO)
  • Echocardiography is a noninvasive ultrasound test that is used to examine the size, shape, and motion of cardiac structures.
important cardiac labs
Important Cardiac Labs
  • Enzymes – CK, CK-MB, LDH
  • Other important cardiac biomarkers that are assessed include the myoglobin and troponin T or I. Myoglobin
slide37

early marker of MI, is a heme protein with a small molecular weight. This allows it to be rapidly released from damaged myocardial tissue and accounts for its early increase, within 1 to 3 hours after the onset of an acute MI. Myoglobin peaks in 4 to 12 hours and returns to normal in 24 hours.

slide38

Lipid studies – Cholesterol, triglycerides

Coagulation studies – PTT and PT/INRI (nternational

  • Normalized Ratio (INR).The INR provides a standard method for reporting PT level
  • Electrolytes – Potassium, magnesium, and calcium
invasive tests
Invasive Tests
  • Cardiac catheterization
  • Coronary angiography
slide41
To pump effectively, large portions of cardiac muscle must receive an action potential nearly simultaneously.
  • Special cells that conduct action potentials extremely rapidly are arranged in pathways through the heart.
slide42
Before mechanical contraction, an action potential travels quickly over each cell membrane and down into each cell’s.
slide43

Three physiologic characteristics of two specialized electrical cells, the nodal cells and the Purkinje cells, provide this synchronization:

  • Automaticity: ability to initiate an electrical impulse
  • Excitability: ability to respond to an electrical impulse
  • Conductivity: ability to transmit an electrical impulse from one cell to another
cardiac conduction1
Cardiac Conduction
  • Sinoatrial (SA) node – Fires at 60–100 beats/minute
  • Intranodal pathway
  • Atrioventricular (AV) node – Fires at 40-60 beats/minute
  • Atrioventricular bundle of His
    • Ventricular tissue fires at 20-40 beats/minute and can occur at this point and down
  • Right and left bundle branches
  • Purkinje fibers
12 lead ecg
12-Lead ECG
  • Limb leads
    • Standard leads: I, II, and III
    • Augmented leads: aVR, aVL, and aVF
  • Precordial leads
    • V1,V2,V3,V4,V5, and V6
  • Axis
    • The direction of the flow of electricity
slide56

EXPLAINING P,Q,R,S&T

P wave : atrial depolarization

up to 0.12 second in duration .

QRS complex : ventricular depolarization normal measure is 0.08-0.12 second

T wave : ventricular repolarization , rounded upright, not exceeds 0.2 sec of duration

PR interval : the interval between the beginning of p wave and the beginning of R wave it measures between ( 0.12-0.2

slide57

EXPLAINING P,Q,R,S&T

ST segment : the isoelectric line between the end of QRS and the beginning of T wave

QT interval : the interval between the beginning of Q wave and the end of T wave , it measures ( 0.32 – 0.40 ) second

normal timing
Normal Timing
  • PR interval – 0.12 to 0.20 seconds
  • QRS interval – less then 0.12
  • QT interval – varies with rate. It is usually less then ½ the R-to-R distance on the preceding waves
steps to reading ecgs
Steps to reading ECGs
  • What is the rate? Both atrial and ventricular if they are not the same.
  • Is the rhythm regular or irregular?
  • Do the P waves all look the same? Is there a P wave for every QRS and conversely a QRS for every P wave?
  • Are all the complexes within normal time limits?
  • Name the rhythm and any abnormalities.
slide60
Rate
  • Look at complexes in a 6-second strip and count the complexes; that will give you a rough estimate of rate
  • Count the number of large boxes between two complexes and divide into 300
  • Count the number of small boxes between two complexes and divide into 1500
  • Estimate rate by sequence of numbers.
normal sinus rhythm
Normal Sinus Rhythm
  • Rate is between 60 and 100 beats/minute
  • The rhythm is regular
  • All intervals are within normal limits
  • There is a P for every QRS and a QRS for every P
  • The P waves all look the same
sinus tachycardia
Sinus Tachycardia
  • Rate above 100 beats/minute
  • The rhythm is regular
  • All intervals are within normal limits
  • There is a P for every QRS and a QRS for every P
  • The P waves all look the same
  • Caused by fever, stress, caffeine, nicotine, exercise, or by increased sympathetic tone
  • Treatment is to take care of the underlying cause
sinus bradycardia
Sinus Bradycardia
  • Rate is lower than 60 beats/minute
  • The rhythm is regular
  • All intervals are within normal limits
  • There is a P for every QRS and a QRS for every P
  • The P waves all look the same
  • Caused by beta-blocker, digitalis, or calcium channel blockers. Normal for athletes
  • Don’t treat unless there are symptoms. Can use pacing or atropine
sinus arrhythmia
Sinus Arrhythmia
  • Rate is between 60 and 100 beats/minute
  • The rhythm is irregular. The SA node rate can increase or decrease with respirations
  • All intervals are within normal limits
  • There is a P for every QRS and a QRS for every P
  • The P waves all look the same
  • More common in children and athletes
  • Ask the patient to stop breathing and the rate will become regular
premature atrial contraction pac
Premature Atrial Contraction (PAC)
  • Can occur at any rate
  • The rhythm is irregular because of the early beat but is regular at other times
  • All intervals can be within normal limits
  • There is a P for every QRS and a QRS for every P
  • The P waves all look the same except the P in front of the PAC will be different
slide69

SUPRAVENTRICULAR TACHYCARDIA

The source of the impulse is some where above ventricles , but the impulse then spread to the ventricles so the heart beats faster than normal .

supraventricular tachycardia svt
Supraventricular Tachycardia (SVT)

Rate is between 150 and 250 beats/minute

The rhythm is regular

QRS intervals can be within normal limits

There can be a P wave, but more likely it will be hidden in the T wave or the preceding QRS wave

Starts and stops abruptly

Treat with Valsalva maneuver or adenosine IV

slide72

SUPRAVENTRICULAR TACHYCARDIA

  • CAUSES :

1- hypothyroidism .

2- anxiety .

3- pericarditis .

4- heart failure .

5- structural abnormality .

slide73

ATRIAL FIBRILLATION

  • Occurs when multiple irritable focuses in both atria started to initiate impulses that resulting in chaotic , irregular excitation of the atrium .
atrial fibrillation
Atrial Fibrillation
  • Atrial rate is between 350 and 600 beats/minute; ventricular rate can vary
  • The rhythm is irregular
  • There is no PR interval; QRS may be normal
  • There are many more f waves then QRS
  • Unlike flutter where the f wave will appear the same, in fib the f waves are from different foci so they are different
atrial fibrillation1
Atrial Fibrillation
  • CAUSES

1- anterior myocardial infarction .

2- inferior myocardial infarction .

3- valvular heart disease .

4- heart failure .

atrial flutter
Atrial Flutter
  • Atrial rate is between 250 and 350 beats/minute. Ventricular rate can vary
  • The rhythm is regular or regularly irregular
  • There is no PR interval. QRS may be normal
  • 2:1 to 4:1 f waves to every QRS
  • There are no P waves; they are now called flutter waves
  • Problem: Loss of atrial kick and ventricular conduction is too fast or too slow to allow good filling of the ventricles
slide79

ATRIAL FLUTTER

  • CAUSES :

1- atrial enlargement .

2- hyper thyroidism .

3- inferior myocardial infarction .

4- anterior myocardial infarction .

slide80

JUNCTIONAL RHYTHM

  • This type occurs when SA node & the atria are unable to discharge an impulse to depolarize both atria & ventricles , therefore an ectopic focus in the surrounding junctional tissue take the responsibility as apace maker at a rate of ( 40-60 ) bpm .
  • The P wave may be absent, inverted & next QRS complex ; depends upon its origin .
junctional rhythm
JUNCTIONAL RHYTHM
  • 1-RHYTHM : regular .
  • 2- RATE : 50 bpm , ( 40 – 60 ) bpm .
  • 3-P WAVE : Absent .
  • 4- QRS COMPLEX : normal configuration & duration .
  • 5- T WAVE : normal .
  • 6- CONUCTION : the atria is stimulated by the junctional tissue after activation after or with the activation of the ventricles .
junctional rhythm1
JUNCTIONAL RHYTHM
  • CAUSES :

1- acute myocardial infarction .

2- digoxin toxicity .

slide85

ACCELARATED JUNCTIONAL RHYTHM

  • 1- RHYTHM : regular .
  • 2- RATE : 83 bpm .
  • 3- P WAVE : after QRS complex .
  • 4- QRS COMPLEX : normal configuration & duration .
  • 5-T WAVE : Normal .
  • 6- CONDUCTION : atria activated after the ventricles so P wave comes after QRS complex .
slide87

ACCELARATED JUNCTIONAL RHYTHM

  • CAUSES :

1- congestive heart failure .

2- cardiogenic shock .

NOTE : this type of arrhythmia start & end gradually .

premature ventricular contractions pvc
Premature Ventricular Contractions (PVC)
  • Early beat that is wide (>0.12)
  • Originates the ventricles
  • No P wave
  • Compensatory pause
  • Can be defined by couplet or triplet; anything more would be considered ventricular tachycardia
  • Monomorphic or polymorphic
slide91

VENTRICULAR ECTOPIC BEAT

  • Multi focal means that the ectopic beat has more than one foci , that discharge many shapes of QRS & T .
slide92

VENTRICULAR ECTOPIC BEAT

  • That means that 2 consequences impulses discharged prior to the next anticipated sinus rhythm impulse .
ventricular tachycardia
Ventricular Tachycardia
  • Rate is between 100 and 200 beats/minute
  • The rhythm is regular, but can change to different rhythms
  • No PR interval; QRS is wide and aberrant
  • There may be a P wave, but it is not related to the QRS
ventricular fibrillation
Ventricular Fibrillation
  • Rapid, irregular rhythm made by stimuli from many different foci in the ventricula
  • Produces no pulse, blood pressure, or cardiac output
  • Can be described as fine or coarse
  • Most common cause of sudden cardiac death
torsades de pointes
Torsades De Pointes
  • Polymorphous ventricular tachycardia
  • Caused by long QT syndrome.
  • This is an inherited condition or caused by antiarrhythmic drugs
  • Cannot be converted by defibrillation
  • Magnesium is the drug of choice
  • Overdrive pacing may work also
slide99

IDIOVENTRICULAR RHYTHM

  • This arrhythmia occurs when all supra ventricular pace makers ( SA node , AV junction , bundle of his , bundle branch ) fail to elicit an electrical impulse ; the ventricles take over as a pace maker , firing at their own inherent rate of ( 30 – 40 ) bpm .
slide101

IDIOVENTRICULAR RHYTHM

1-RHYTHM : regular R-R interval .

2- RATE :(30-40) bpm .

3- P WAVE : absent .

4-QRS COMPLEX : wide & bizarre .

5- CONDUCTION : electrical impulses arises from the purkinji fibers or ventricular myocardium .

idioventricular rhythm
IDIOVENTRICULAR RHYTHM
  • CAUSES :

1- cardiogenic shock .

2- medication effects like adrenaline .

slide103

ACCELERATED IDIOVENTRICULAR RHYTHM

  • This arrhythmia occurs when the SA node & AV junction fail to initiate impulse the ventricles take over the role as a pace maker at a rate about ( 50-100) bpm .
accelerated idioventricular rhythm
ACCELERATED IDIOVENTRICULAR RHYTHM
  • 1-RATE : 60 bpm .
  • 2- RHYTHM : regular R-R interval .
  • 3- P WAVE : absent .
  • 4- QRS COMPLEX : wide & bizarre .
  • 5- T WAVE : caught up in ST segment .
  • 6- CONDUCTION : pace maker site is in bundle branch , purkinji fibers or myocardium
slide106

ACCELERATED IDIOVENTRICULAR RHYTHM

  • CAUSES :

1- Acute myocardial infarctions .

2- digoxin toxicity .

slide108

FIRST DEGREE AV BLOCK

  • Occurs when there is a delay in the transmission of electrical impulse through the AV node to the ventricles .
slide110

FIRST DEGREE AV BLOCK

1- RHYTHM : regular .

2- RATE : 45 bpm < 50bpm

3- P WAVE : normal .

4- P-R INTERVAL : 0.28 seconds

5- QRS COMPLEX : normal .

6- CONDUCTION : follow normal conduction pathway but there is a delay in the process .

slide111

SECOND DEGREE AV BLOCK MOBITZ-1

  • Occurs when conduction through the AV junction become progressively difficult with each successive impulse until finally a ventricular depolarization doesn’t occur .
slide113

SECOND DEGREE AV BLOCK MOBITZ-1

  • 1-Ventricular and atrial rate :Depends on the underlying rhythm
  • 2- RHYTHM : atrial regular , but ventricular irregular .
  • 3- P WAVE : normal .
  • 4-P-R INTERVAL : lengthening with each successive beat .
  • 5-QRS COMPLEX :normal .
slide114

SECOND DEGREE AV BLOCK MOBITZ-1

  • 6- CONDUCTION : some of the impulses from the atria are blocked . P-R interval gets progressively longer until one P wave is not followed by QRST .
slide115

SECOND DEGREE AV BLOCK MOBITZ-1

  • CAUSES :

1-rehumatic fever .

2- inferior myocardial infarction .

3- digoxin toxicity .

slide116

SECOND DEGREE AV BLOCK MOBITZ-2

  • In this arrhythmia 2 or more atrial impulses conducted normally , then the next impulse blocked without warning . Block may occur occasionally or at regular intervals . ( for every third beat ) ( 3:1) .
slide118

SECOND DEGREE AV BLOCK MOBITZ-2

  • 1-Ventricular and atrial rate :Depends on the underlying rhythm
  • 2- RHYTHM : P-P interval regular , R-R interval irregular .
  • 3- P WAVE : normal .
  • 4- P-R INTERVAL : 0.16 sec , absent in missed beats .
slide119

SECOND DEGREE AV BLOCK MOBITZ-2

  • 5- QRS COMPLEX : normal, some dropped beats .
  • 6- T WAVE : normal , some dropped as QRS
  • 7- CONDUCTION : Third atrial impulse is blocked .
slide120

SECOND DEGREE AV BLOCK MOBITZ-2

  • CAUSES :

1- degenerative changes in conduction system

2- anterior myocardial infarction .

3- coronary artery disease .

slide121

COMPLETE HEART BLOCK

  • Occurs when the electrical impulses above the AV node are blocked , therefore no impulses conducted to the ventricles , if SA node blocked the junctional arises , if the block involve the junctional tissue , the idiodventricular rhythm arises .
slide123

COMPLETE HEART BLOCK

  • 1-1-Ventricular and atrial rate :Depends on the underlying rhythm
  • 2- RHYTHM : P-P interval regular , R-R interval regular .
  • 3-P WAVE : normal .
  • 4-P-R INTERVAL : absent ( no relation between atria& ventricles )
slide124

COMPLETE HEART BLOCK

  • 5- QRS COMPLEX : depend on the site of pace maker , ( wide = purkinji fibers ) ( normal =junctional tissue )
  • 6- T WAVE : absent .
  • 7- CONDUCTION : the atria & ventricles have independent pacemaker ,so there is no relationship between both .
slide125

COMPLETE HEART BLOCK

  • CAUSES :

1-inferior myocardial infarction .

2- digoxin toxicity .

3- degeneration of conduction system .